Any way to get access to a callback for progress updates? (for React)

I’m using React instead of Blaze, so I can’t use the {{progress}} helper. Is there any way I can set up a callback or event listener to handle progress updates?

[geetwo]

oh my appologies @spawn-guy, here is how i used it to upload mp3 files with Meteor and react.

server/slingshot.js

Slingshot.fileRestrictions( "uploadToAmazonS3", {
  allowedFileTypes: [ "audio/mp3"],
  maxSize: 16 * 1024 * 1024
});

Slingshot.createDirective( "uploadToAmazonS3", Slingshot.S3Storage, {
  bucket: "<my-bucket-name>",
  acl: "public-read",
  region: "my-default-region",
  authorize: function () {
    return true;
  },
  key: function ( file , metaContext ) {
    //metaContext is used here to dinamically construct the file path
    return metaContext.prePath + file.name;
  }
});

imports/ui/components/song-upload.js

*I use react-dropzone to select the file and upload using mu Slingshot directive insde onDrop:

 onDrop(quality, files) {

      //Amozon Path prefix for the file returns something like
         // 'artist/album/128 (or 320)/'
      const pathPrefix = getPathPrefix( this.props.album, quality);
      const metaContext = {prePath: pathPrefix};

      //Upload file using Slingshot Directive
      let uploader = new Slingshot.Upload( "uploadToAmazonS3", metaContext);

      uploader.send( files[0], ( error, url ) => {

        computation.stop(); //Stop progress tracking on upload finish
        if ( error ) {
            this.setState({ progress: 0}); //reset progress state
        } else {
            this.setState({ url: url });
        }
      });

      //Track Progress
      let computation = Tracker.autorun(() => {
          if(!isNaN(uploader.progress())) {
            this.setState({ progress: uploader.progress() * 100 });
          }
      });
   }

[gsuess]

You don’t have to poll it. A better way is to the use Tracker.autorun:

uploader.send(this.props.file, function (error, url) {
  computation.stop(); // Stop the computation in order to save memory.
  //...
});

var computation = Tracker.autorun(function () {
  self.setState({progress: uploader.progress()});
});